Traffic routes today have a great variety of road signs. In particular, the multitude of signs, also generally referred to as a traffic-sign jungle, make a motor vehicle driver less and less apt to recognize the road signs or more likely to forget the same. Therefore, driver assistance systems have been developed, to be provided in the dashboard, for example, in order to inform the driver of currently valid road signs.
Thus, for example, European Patent No. EP 1 826 736 A1 describes a vehicle having a road-sign recognition device which includes a camera, a control device for determining a potential road sign contained in the camera image and/or the regulatory content thereof, and a display for outputting a representation of the road sign or information relating to the regulatory content thereof.
Moreover, the German Patent Application No. DE 10 2007 048 842 A describes a driver assistance system for signaling wrong-way driving. The control device it describes includes an input for receiving image information captured by a camera, the image information relating to specific objects in the vicinity of the vehicle, whose front view differs from its rear view. An evaluation component is also provided for analyzing the image information in order to identify the front and rear views of the particular objects, as is a decision component for deciding if an output signal is to be generated on the basis of the information ascertained by the evaluation component, the output signal relating to the correctness of the momentary vehicle driving direction.
Besides a camera, a digital map is frequently used as well to determine the currently valid road sign. However, such a digital map quickly becomes outdated since road signs used for road traffic are frequently changed. This is attributable, for example, to modifications to the road routing, fluctuating traffic densities, and road maintenance work, etc.
Current systems, which assist the driver during a vehicle, in particular motor vehicle trip, provide for all possible information to be communicated to the driver. From all of this information, the driver is able to assess the momentary situation and adapt his/her driving behavior accordingly.
Conventionally, the use of a digital map and a camera are combined in various fields and implementations. Thus, for example, International Patent Application No. WO 2000/016214 A describes a method, respectively a coupled system used in road-sign recognition and navigation that permits a bidirectional data transmission between a road-sign recognition device and a navigation device. Thus, information can be exchanged between the two systems.
In all of these conventional devices and methods, it has proven to be disadvantageous that contradictory information from the map and recognition device cannot be optimally processed due, for example, to obsolescing map information or because the reliability determination made by the road-sign recognition device is typically not adapted to the ambient situation.